Umm.. this may only be an accepted rule of thumb for my area of the good old red-white-and-blue.. but if we hear someone speaking with a british accent, and they say things that we don't really understand. we just (mentally) shrug out shoulders and chalk it up as "those english and their language*. If you try and pick up a british accent, then travel to america.. then you may be given more leeway (room for making errors), as noone really knows what the english are talking about half the time. I know, I listened to an english shop owner in my area, and pretty much just listened to her accent and nodded a lot. ^^;;
........

In all seriousness, there will be words which do not translate very well, in either how they are used in a sentence, how they are pronounced, or.. OH, something important. If you understand the word, and are comfortable with saying it's translated counterpart.. then also associate that word with a facial expression if it is a very serious topic or a very relaxed topic. So when you are talking about a serious matter with someone, use a serious facial expression. But when you are speaking about something everyday or something funny.. use a relaxed facial expression. Even when we don't understand the words, understanding someone's facial expression helps to fill in the gaps.. some.